Analysis and management strategies for the low voltage problems of rural power grid based on the distribution network flow calculation method

For a long time, because of the lack of investment capital and enough attentions, the overall constructions of rural power grid were far behind than the urban power grid in Chongqing Jiangbei Power Company. The low voltage problems were highlighted in the rural power grid due to the characteristics of rural power grid. Using the distribution network flow calculation method, we evaluated the low voltage problems of the rural power grid which belongs to Chongqing Jiangbei Power Company. In addition, we collected the data of distribution transformers in electricity consumption peak period. Some practical management strategies were proposed by the analysis and evaluation of potential and appeared low voltage problems.

Comparison the Performances of Three Earthing Systems for Micro-Grid Protection during the Grid Connected Mode

This paper presents, tests and compares three earthing systems (TT, TN and IT) for Micro-Grid (MG) protection against various fault types during the connected mode. The main contribution of this work is including the models of all the micro sources which interfaced to the MG by power electronic inverters. Inverters in turns are provided with current limiters and this also included in the inverter models to exactly simulate the real situation in the MG during fault times. Results proved that the most suitable earthing system for MG protection during the connecting mode is the TN earthing system. That system leads to a suitable amount of fault current sufficient to activate over current protection relays. With using TN system, Touch voltages at the faulted bus and all other consumer’s buses are less than the safety limited value if current limiter is included with the transformer of the main grid which connects MG. For the two others earthing systems (TT and IT), fault current is small and nearly equal to the over load current which make over current protection relay can not differentiate between fault current and overload current. All models of micro sources, earthing systems, inverters, main grid and control schemes are built using Matlab?/Simulink? environment.

A Pathway to Explore the Hidden Specialty in the Design of Fifteen Level Inverter in Grid Connected PV System

This research paper proposes a single phase fifteen level inverter for a grid connected PV system.The proposed inverter is also called cascaded asymmetric multilevel inverter.By adopting appropriate hybrid modulation technique improved output voltage is obtained with minimum number of power electronic switches.By reducing the number of gate triggering circuits of the switches,the size and power consumption of the driving circuits can be reduced.The total harmonic distortion of the output of the inverter is improved by this inverter.The proposed inverter developed by cascading a full bridge inverter with modified H bridge multilevel inverter.The validity of the proposed system is verified through MATLAB simulations.

Analyzing the Impact of Bapco 5 MW Solar PV Grid-Connected Project on Bahrain’s Outlook for Energy-Mix Production

The impact of Bapco 5 MW solar PV grid-connected project on Bahrain’s outlook for clean energy and energy-mix production was analyzed since solar electricity obtained from PV installation is considered as a non-linear system. Several positive impacts were counted. These impacts were on business, economy, environment, research, green jobs creation and rooftop installation and other large-scale installation. This project had attracted public, investors, developers to invest in similar projects in the Kingdom of Bahrain;especially it is an environmentally friendly and smart technology. This innovative smart grid-connected 5 MW solar PV power plant is enough to electrify 500 houses @ 10 kW and had answered lots of frustrating questions such as the effect of dust on PV performance, need of man-made cleaning compared to naturally cleaned PV panels, reliability of the system, greenhouse gases reduction and pay-back period.

Review of Modeling Methods of Distributed Energy Supply System Connected to the Grid

At present, the development of distribution network can’t meet the requirements of rapid economic development. The traditional single energy supply is difficult to meet the request, and distributed energy supply has a lot of advantages compared to it, particularly it's close to the end users, and they have been developed well and applied widely in recent years. This paper summarizes the features and current development of the distributed energy supply, and mainly describes the grid-connection model of distributed energy supply. Base on the mathematic grid-connection model of distributed power sources with different generation principles as well as that energy storage, the treatment of these models in distribution network power flow analysis is also presented.

Evaluation of the Performances of the First Grid-Connected Photovoltaic System in Sénégal

This document presents the evaluation and the monitoring of the performances of the first grid-connected photovoltaic system installed in the Center of Studies and Researches on the Renewable Energies (CERER) inaugurated on December 4th, 2012 by the governmental authorities of Senegal and Tenerife. This mini power plant of 3.15 kWc is a perfect example of the political will of the government which is to reduce the production cost of the electricity, with the diversification of the sources of production, and the greater use of the other sources such as the natural gas, the coal, the renewable energies. The evaluation of the performances of the installation is realized by using the indicators of efficiency and performance as the photovoltaic surface yield, the ratio of photovoltaic performance, the photovoltaic specific yield, and the losses of captures. The obtained results show that a big part of the energy shone during the period of observation was not able to be used further to circumstances such as the losses of conductivity, the heat losses or for example the defects on components. The analysis also shows that a large part of the produced energy is not injected because of the dilapidation of the network, the defects of landing but especially one disjunction sees frequently at the level of the point of injection.

Forecast of Power Generation for Grid-Connected Photo-voltaic System Based on Grey Theory and Verification Model

Being photovoltaic power generation affected by radiation strength, wind speed, clouds cover and environment temperature, the generating in each moment is fluctuating. The operational characteristics of grid-connected PV systems are coincided with gray theory application conditions. A gray theory model has been applied in short-term forecast of grid-connected photovoltaic system. The verification model of the probability of small error will help to check the accuracy of the gray forecast results. The calculated result shows that the ?model accuracy has been greatly enhanced.

Electromechanical Transient Modeling Analysis of Large-Scale New Energy Grid Connection

The synchronous virtual machine uses inverter power to imitate the performance of the conventional synchronous machine.It also has the same inertia,damping,frequency,voltage regulation,and other external performance as the generator.It is the key technology to realize new energy grid connections’stable and reliable operation.This project studies a dynamic simulation model of an extensive new energy power system based on the virtual synchronous motor.A new energy storage method is proposed.The mathematical energy storage model is established by combining the fixed rotor model of a synchronous virtual machine with the charge-discharge power,state of charge,operation efficiency,dead zone,and inverter constraint.The rapid conversion of energy storage devices absorbs the excess instantaneous kinetic energy caused by interference.The branch transient of the critical cut set in the system can be confined to a limited area.Thus,the virtual synchronizer’s kinetic and potential energy can be efficiently converted into an instantaneous state.The simulation of power system analysis software package(PSASP)verifies the correctness of the theory and algorithm in this paper.This paper provides a theoretical basis for improving the transient stability of new energy-connected power grids.

Implementation of FPGA Based MPPT Techniques for Grid-Connected PV System

Global energy demand is growing rapidly owing to industrial growth and urbanization.Alternative energy sources are driven by limited reserves and rapid depletion of conventional energy sources(e.g.,fossil fuels).Solar photovol-taic(PV),as a source of electricity,has grown in popularity over the last few dec-ades because of their clean,noise-free,low-maintenance,and abundant availability of solar energy.There are two types of maximum power point track-ing(MPPT)techniques:classical and evolutionary algorithm-based techniques.Precise and less complex perturb and observe(P&O)and incremental conduc-tance(INC)approaches are extensively employed among classical techniques.This study used afield-programmable gate array(FPGA)-based hardware arrange-ment for a grid-connected photovoltaic(PV)system.The PV panels,MPPT con-trollers,and battery management systems are all components of the proposed system.In the developed hardware prototype,various modes of operation of the grid-connected PV system were examined using P&O and incremental con-ductance MPPT approaches.

Steady-State Analysis of Grid-Connected New Energy Power Plants

In order to ease the fossil energy crunch,new energy sources need to be fully utilized.Clean energy sources such as wind,light,and nuclear energy are important tools to solve environmental and energy problems.However,in the process of researching new energy farms,there are some problems when they are integrated into the power system.In order to ensure the stability of new energy power plants,it is necessary to conduct an in-depth analysis of the grid connection technology of new energy farms.In the study,it is necessary to learn about the specific problems of the stability of the grid connection of new energy power plants,and to clarify the specific application of the grid connection technology of new energy power plants from the application principle and advantages of the grid connection technology of new energy power plants.Through simulation experiments,the positive effect of grid connection technology of new energy power plants in improving the stability of power systems was determined.

Integrating Smart Building Energy Data into Smart Grid Applications in the Intelligent Secondary Substations

Automation has arrived in the low voltage grid domain. In the next few years, the secondary substation—at the barriers of medium and low voltage grids—will thus be upgraded to enable novel functions. In this paper, we present various smart grid applications running on such intelligent secondary substations(iSSN) including their interaction with each other. We integrate energy consumption and production data, as well as forecasts, sensed from the smart buildings’ energy management systems(BEMSs) into the operation of the low voltage grid. A suitable framework for those modular applications includes features to initiate their installation, update, removal, the remote operator site, and not requiring staff on-site for such typical reappearing maintenance tasks.

Renewable Energy Based Grid Connected Battery Projects around the World—An Overview

The environmental pollution,as well as gradual depletion of mineral resources has encouraged the world to move into renewable energy sources for generation of electricity.At present,the cost of using renewable energy sources,such as sunshine and wind in electricity generation has significantly reduced.This has led to higher penetration of renewable energy into the grid.However,both wind and solar energy photovoltaics are unpredictable energies which reduce the reliability and resiliency of the grid.The integration of battery energy storage system in the grid is one of the proficient solutions to the problem.There are numerous grid connected renewable energy based battery projects that have been deployed in different countries around the world for research,development and commercial application.This review paper will discuss some of the projects based on the battery connected wind and solar energy power generation systems that can operate both in grid connected and grid independent modes.The projects discussed in this paper are selected based on the availability of information.The battery energy storage system(BESS)incorporated in each of the project is found to increase the stability and performance of the grid by addressing the mismatch between power generation and the load of the grid created due to intermittent nature of renewable energy sources.

Feasibility Study for a Hybrid Power Plant(PV-Wind-Diesel-Storage)Connected to the Electricity Grid

In this work,we present a feasibility study for a new hybrid power plant(PV-Wind-Diesel-Storage)directly connected to the electrical grid.Several simulations are performed to verify the performance of the hybrid system under different scenarios using real meteorological data.It is shown that the performances of the hybrid system connected to the electrical network depend obviously on the available energy resources and constraints because the renewable energies are intermittent.In addition,the price of the kWh of electricity supplied by the hybrid system is determined,which amounts to$0.209/kWh,which is very cost effective and satisfactory for the considered sample conditions(Comoros Island).

The Research and Design of the Application Domain Building Based on GridGIS

According to the characteristic of Grid geographical information system (GridGIS), data distribution, heterogeneity and diversity in the grid environment, combining the high demand for shared resources and the purpose to realize unified and efficient management and sharing of distributed and mass resources, this paper proposed a grid GIS application building program on a number of peer-to-peer global Managers designs. This paper discussed the building process of the application domain, the selection criteria of application domain manager, the database design of application domain, and every service function module design of application domain. The integration of the application domain builds the three-tier management system of the node, the application domain, and the global management. The spatial query tests of distributed environment have shown that, the application domain is established to manage and share the distributed resources efficiently, and enhance the business processing functions in the grid environment.

Insights from Stakeholders of Five Residential Smart Grid Pilot Projects in the Netherlands

This paper presents insights and perceptions of stakeholders involved in the development and implementation of residential smart grid pilot projects in the Netherlands, adding to the limited information that is currently available in this area, while expectations about the potential benefits of smart grids are high. The main research questions of this study are: (1) How have some typical residential smart grid pilots in the Netherlands been set up? (2) Which stakeholders are involved in these pilots in the year 2014? (3) What are their views and perceptions with regards to the development and performance of residential smart grids? and (4) What do these stakeholders think about the products and services that may support an active participation of end-users in a smart energy home? To obtain information, we evaluated five residential smart grid pilot projects where smart energy products and services have been implemented. Semi-structured interviews were conducted with nine stakeholders involved in these projects. The Strategic Niche management framework was used to identify the present state of development and implementation of smart grid pilots. Our study shows that in the Netherlands residential smart grid pilots have been set-up and funded mainly by the government and grid operators. Other stakeholders involved include energy suppliers, end-users (as an energy cooperative or individual household), product and service suppliers, Information and Communication Technology (ICT) companies, and knowledge institutes. Currently a technology-push approach exists which barely includes an integrated approach towards smart grids products and services development. To the opinion of the interviewed stakeholders, current products and services offered in residential smart grid pilots are functionally attractive, but often too technically complex for the understanding of end-users. Hence, the general view held by respondents is that end-users should be the starting point in the development of smart grid products and services at the residential areas.

Soft-switching Grid-connected PV Inverter With Interleaved Flyback Topology

提出一种应用于单个光伏组件的软开关交错反激并网逆变器拓扑及其软开关控制策略。针对反激变压器漏感问题，提出漏感能量吸收回馈电路，实现了漏感能量吸收再利用，并实现了开关管漏源电压的钳位，提高了变换效率同时降低了开关管关断电压尖峰；提出基于数字处理器的反激变换器变开关频率谐振软开关控制策略，实现了开关管的零电压开通，同时改善了逆变器的电磁兼容特性；提出的交错并联反激逆变器有助于减小变压器和滤波器的体积，提高功率密度。详细分析变换器的工作原理，分析变开关频率谐振软开关控制方式的原理和实现条件，最后进行实验验证。